<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>js_object</title>
    <style>
        *{margin: 0;padding: 0;}
        div{width: 100px;height: 100px;}
        #div1{background-color:blue;}
    </style>
    <script>
        window.onload = function(){
            document.getElementById("div1").addEventListener("click",function () {
                this.style.width = 200+'px';
                this.style.height = 200+'px';
            });
            document.getElementById("div1").onmouseleave=function () {
                this.style.width = 100+'px';
                this.style.height = 100+'px';
            };
        }
    </script>
</head>
<body>
<div id="div1">


</div>
</body>
<ml>